Investigating morphological changes in the brain in relation to etiology and duration of olfactory dysfunction with voxel-based morphometry.

Olfactory loss (OL) affects up to 20% of the general population and is related to changes in olfaction-related brain regions. This study investigated the effect of etiology and duration of OL on gray matter volume (GMV) of these regions in 257 patients. Voxel-based morphometry was applied to measure GMV in brain regions of interest to test the effects of etiology and duration on regional GMV and the relation between olfactory function and regional GMV. Etiology of OL had a significant effect on GMV in clusters representing the gyrus rectus and orbitofrontal cortex (OFC), bilaterally. Patients with congenital anosmia had reduced GMV in the gyrus rectus and an increased OFC volume compared to patients with acquired OL. There was a significant association between volume of the left OFC and olfactory function. This implies that changes in GMV in patients with acquired OL are mainly reflected in the OFC and depend on olfactory function. Morphology of olfactory areas in the brain therefore seems to relate to olfactory function and the subsequent degree of exposure to olfactory input in patients with acquired OL. Differences in GMV in congenital anosmia are most likely due to the fact that patients were never able to smell.

Validation of animal experiments on ciliary function in vitro. I. The influence of substances used clinically.

In vitro studies of ciliary activity require specimens of healthy epithelium in relatively large quantities. Since human material is difficult to obtain, fresh chicken trachea samples have frequently been used in function experiments. The aim of the present study was to investigate whether several substances had comparable effects on the ciliary beat frequency (CBF) of chicken trachea and cryopreserved human respiratory epithelium obtained from the sphenoidal sinus. For this study, we used two topical anaesthetics: cocaine (3% and 7%) and lidocaine (2%). These anaesthetic substances were adjusted to pH 6 and pH 7. We also used two decongestants, namely xylometazoline 0.1% and oxymetazoline 0.1%, and the beta-blocking agent propranolol. Topical anaesthetics appeared to be more ciliostatic in solutions with pH 7 compared to pH 6. Complete ciliostatic effects were reversible, with the exception of the ciliostasis induced by propranolol. The effects of these substances on the CBF of fresh chicken trachea and cryopreserved human tissue did not differ significantly. These experiments show that chicken trachea constitutes a valid substitute for human material in studying ciliary activity in vitro. Moreover, the experiments provide evidence in support of the assumption that cryopreservation has no effect on ciliary reactivity as expressed by the CBF.

Validation of animal experiments on ciliary function in vitro. II. The influence of absorption enhancers, preservatives and physiologic saline.

Ciliary beat frequency (CBF) is one of the most important parameters of mucociliary clearance. Previously, we demonstrated that mucosa from chicken embryo trachea is a good substitute for human ciliated epithelium to study the effects on CBF of substances that are used clinically. In this study, we examined the effect on CBF of four excipients for nasal drug formulations: the absorption enhancers methylated beta-cyclodextrin 2% and sodium taurodihydrofusidate 1%, the preservative benzalkonium chloride 0.01%, and physiologic saline. We also examined the effect on CBF of the cryopreservative dimethyl sulfoxide, which is used to protect ciliated epithelium prior to storage in liquid nitrogen. Results obtained with chicken embryo trachea were compared with those of cryopreserved human mucosa taken from the sphenoidal sinus. For all of the substances tested, the effects on CBF of chicken material were comparable to those measured on human material. Benzalkonium chloride had a stronger ciliostatic effect on human tissue. After 60 min, however, the effect of that substance on CBF was similar in both tissues. We conclude that chicken embryo trachea can be used as a substitute for human ciliated mucosa when studying ciliary activity in vitro.

Physiologic and hypertonic saline solutions impair ciliary activity in vitro.

OBJECTIVE/HYPOTHESIS: Physiologic saline (NaCl 0.9%) is commonly used in treating acute and chronic rhinosinusitis. Moreover, physiologic saline is used as a control medium, vehicle, or solvent in studies on ciliary beat frequency (CBF). Hypertonic saline (NaCl 7% and 14.4%) has been applied in attempts to enhance mucociliary transport in patients with cystic fibrosis or asthma and in healthy subjects. Therefore the objective of this study is to document in vitro effects of saline solutions in different concentrations on CBF. STUDY DESIGN: Experimental, in vitro. METHODS: The effects on CBF of cryopreserved mucosa of the sphenoidal sinus was measured by a photoelectrical method. Initial frequencies, measured in Locke-Ringer's solution (LR), were compared with CBF after exposure to NaCl in concentrations of 0.9%, 7.0%, and 14.4% (w/v). RESULTS: NaCl 0.9% has a moderately negative effect on CBF. The 7% solution leads to a complete ciliostasis within 5 minutes, although this effect turns out to be reversible after rinsing with LR. A hypertonic solution of 14.4% has an irreversible ciliostatic effect. CONCLUSION: LR is an isotonic solution that has no effect on CBF. Therefore it is probable that this solution is more appropriate than saline for nasal irrigation and nebulization or antral lavage. Moreover, the results of this study suggest that mucolytic effects induced by hyperosmolarity should be attained preferably with hypertonic saline 7% in patients with cystic fibrosis or asthma. At this concentration, the ciliostatic effect is reversible, whereas irreversible changes are to be expected at higher concentrations.

Ciliary beat frequency of human sphenoid sinus mucosa after cryopreservation.

In vitro studies of human ciliary activity require relatively large quantities of specimens of healthy ciliated epithelium. For this reason we investigated whether cryopreserved healthy mucosa taken from the sphenoid sinus during pituitary surgery would meet the demands of this type of study. The sinus mucosa from ten patients was immersed in two different cryopreservatives. One solution contained 10% dimethylsulfoxide (DMSO) as cryoprotector. The other contained glycerol as a part of human sperm preservation medium (HSPM). The ciliary beat frequency (CBF) was measured sequentially by a photoelectrical method: when specimens were fresh and then at intervals of 1 week, 1 month and 3 months after cryopreservation in liquid nitrogen and thawing. Mean CBF values recorded after thawing did not differ significantly from the values measured before cryopreservation. Prior to cryopreservation and after thawing, CBF did not change during a period of 4 h. Epithelia preserved in DMSO demonstrated that the low mean CBF (5.4 Hz) found was caused by a reversible ciliostatic effect of the medium. After thawing and rinsing with a neutral medium, CBF showed normal values. We conclude that sphenoid sinus mucosa is an appropriate source of ciliated mucosa for in vitro experiments. Since non-pathological ciliated epithelium can be maintained in a "mucosa bank," our finding makes further studies of CBF of normal human respiratory epithelium in vitro a realistic goal.